1. Field of the Invention
The present invention relates to a developing apparatus utilizing a one-component type toner and more particularly, to a developing apparatus for use in image forming apparatuses utilizing an electrostatic latent image, such as electrophotographic copying machines and the like.
2. Description of the Related Art
A conventional development technique employed by the developing apparatus for use in the electrophotographic copying machines, which utilizes the one-component type toner, is generally arranged such that a layer-thickness regulating member is in widthwise contact with a rotated toner carrier for uniformalizing a thin toner layer on the toner carrier while the toner is imparted with a charge required for image development through triboelectrification, charge injection or a combination of both techniques. According to a well-known development technique, the thin toner layer is transported to a contact portion between an image bearing member and the toner carrier for development of an electrostatic latent image on the image bearing member.
In order to accomplish stable layer-thickness regulation as one of the conditions for forming images of good quality, this technique typically adopts a method in which the layer-thickness regulating member, such as of a cantilevered structure formed of a metal sheet, a high polymer resin or a lamination of both materials, has its surface or leading edge abutted against the toner carrier via the toner.
Unfortunately, the prior-art layer-thickness regulating member suffers an occurrence of vibration thereof which may result from a changed abutment state due to the deterioration thereof with time, stick slip associated with the rotation of the developer carrier, vibration transferred from a drive source such as a motor, foreign matters entered in or deposited at the abutment portion or the like. Such a vibration interferes with the forming of a toner layer of a uniform thickness, thus resulting in images with quality lowered by density variations, unwanted tone variations, fogs, contamination and the like. Additionally, the vibration of the layer-thickness regulating member also causes the toner to be scattered or spilled from a developer chamber and hence, contamination of resultant images, increases in toner consumption, a contaminated interior of the apparatus with the toner or the like will result.
Furthermore, at opposite sealing portions of the layer-thickness regulating member which are pressed against sealing members for preventing the toner from being scattered or spilled from opposite end portions thereof, the vibration of the layer-thickness regulating member associated with the rotation of the developer carrier causes a similar toner sealing failure to the above. Such a toner sealing failure causes the toner to be scattered or spilled, thus resulting in drawbacks such as contamination of resultant images or the interior of the apparatus, an increased toner consumption and the like.
The sealing portions of the layer-thickness regulating member are particularly susceptible to the vibration because the sealing portions define edge portions of the layer-thickness regulating member, and the layer-thickness regulating member tends to be in direct contact with a surface of the rotating toner carrier without the toner interposed therebetween, the toner preliminarily removed by the sealing member upstream of the sealing portions. In addition, there is a fear that the sealing portions themselves may produce the vibration which causes a toner leakage therefrom or which is transferred to the layer-thickness regulating member thereby to drive the regulating member into vibration.